Windows 98 on CD

Step Seven: the IO.SYS trick

At this point we begin the preparations that are outside the OS.  These are as important as the previous steps, and this one is particularly necessary. Without it, the system will try to boot windows with any type of previous registry. In effect, if you are trying to repair any previously deranged system, it will never get past your old botched registry files.  What we’re doing here is telling windows to use system.tat instead of system.dat.  Here’s what to do:

a.       hex edit io.sys(make sure you’ve made it visible and read/write) , replacing all instances of system.dat with system.tat

b.      If you have yet to do so, unzip your windows archive, rename system.dat to system.tat, and zip it back up again.

c.       I also hex edit scanreg.exe and replace system.dat with system.tat. This makes it much easier to fix registry files if they show a problem.